JPH0218445B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a thrust bearing having a sliding surface that slides under a thrust load. [Problems to be solved by the conventional technology and the invention] When using a conventional thrust bearing, unlike a radial bearing, a wedge oil film is not easily formed due to rotation of the shaft, and the surface (thrust surface) that allows sufficient oil to slide is difficult to form.
It is difficult to supply this material to the surface, and it is often used in a so-called boundary lubrication state. As described above, thrust bearings are always subjected to harsher conditions than radial bearings, so it is common practice to provide oil reservoirs, oil grooves, etc. on the thrust surface to improve oil supply and friction conditions. However, although this processing increases costs, a fully satisfactory product has not yet been obtained. In addition, recently, due to the miniaturization and improved performance of equipment, there is a tendency for equipment to be used under harsher lubrication conditions such as higher loads and higher speeds. In such cases, conventional thrust bearing materials could only be used in conjunction with special oil supply devices, complicated bearing structures, or expensive special alloys, which would result in a significant increase in costs. On the other hand, it is also known that a metal film is formed on the surface of the bearing. Japanese Patent Publication No. 55-2441 discloses that on a steel plate or a steel plate plated with Ni or the like, a first sintered layer of A1 metal, and a second sintered layer made of A1 metal and a solid lubricant, etc. Discloses a sliding material on which are sequentially placed. JP-A No. 55-2747 discloses a sliding member in which the surface of an iron-based metal is subjected to sulfur-nitriding treatment, and a metal coating layer is formed on the surface. However, when used constantly under harsh conditions like a thrust bearing, the corrosion resistance is insufficient, and as a result, the performance of the thrust bearing deteriorates or becomes unstable. The present invention aims to eliminate the above-mentioned drawbacks, and in particular, enables good sliding even under severe thrust bearing usage conditions, is inexpensive, has excellent corrosion resistance, and has good sliding properties. The present invention aims to provide a thrust bearing having the following characteristics. [Means for Solving the Problems] The present invention has been made in view of the above-mentioned background, and has a structure in which, in a thrust bearing having a sliding surface that slides under a thrust load, the sliding surface of the thrust bearing is This is a thrust bearing comprising a soft nitrided film applied on a moving surface, and a lubricating film containing a resin binder and a solid lubricant formed on the soft nitrided film. Furthermore, the solid lubricant includes at least one selected from molybdenum disulfide, graphite, boron nitride, tungsten disulfide, and polytetrafluoroethylene resin. [Function] Specifically, the thrust bearing according to the present invention has the following features:
A base material made of a metal material such as Fe or its alloy that has sufficient mechanical strength against large impact loads, a soft nitrided film applied to the sliding surface side of the base material, and a soft nitrided film applied to the sliding surface of the base material. Since it is composed of a lubricating film containing a resin binder and a solid lubricant formed by coating or the like on top, it has excellent corrosion resistance, etc., as will be described in detail later. First, each configuration will be described. As the metal material, carbon steel (such as SPCC), which is a metal with sufficient mechanical strength, can be used. The above-mentioned solid lubricant is preferably one that itself has excellent corrosion resistance, such as molybdenum disulfide,
Graphite, boron nitride, tungsten disulfide, polytetrafluoroethylene resin, etc. can be used, and one or a combination of two or more of these can be used. As the resin binder, thermosetting resins such as epoxy resins and phenolic resins can be used. This, in addition to the above solid lubricant as a binder,
Applied as a lubricating film. This resin binder itself also has excellent corrosion resistance. A member on which a lubricating film containing a resin binder and a solid lubricant is formed has an extremely smooth surface and a layer of solid lubricant, compared to a member formed only from steel or aluminum alloy.
The coefficient of friction remains extremely low and constant because the smoothness between the layers of the flaky structure creates an oil-sliding effect. The lubricating film provides corrosion resistance. If SPCC is used as the base material on which the soft nitrided film is applied, and molybdenum disulfide, which is the most preferred solid lubricant that forms the lubricating film together with the resin binder, is used, the friction coefficient of the soft nitrided film and the member on which the lubricating film is formed can be reduced. is very small at 0.02 to 0.1,
Load capacity is higher than 2800Kg/ ^cm2 . The nitrocarburizing treatment is performed in advance as a base film forming treatment when forming a lubricating film containing this solid lubricant. This nitrocarburizing film not only improves the adhesion and stability of the lubricating film to the base material made of metal, but also particularly improves the corrosion resistance of the base material and the lubricating film. Although its effect is not clear, it is thought to be as follows. In other words, with conventional products that have a surface film made of metal, corrosion of the base material may occur due to partial peeling, or corrosion may occur from the surface of the base material, and furthermore, it may cause poor adhesion at this interface. In the worst case, it will peel off. On the contrary,
In the present invention, the soft nitrided film prevents the surface of the base material from corroding, and the adhesion strength between the resin binder and the lubricating film containing the solid lubricant is high, and the soft nitrided film prevents the surface of the base material from being corroded. As a result of the synergistic effect with the effect of protecting the side surfaces, corrosion of the base material and the lubricating film is effectively prevented. moreover,
In a film containing a resin binder and a solid lubricant,
Even if there is no peeling part as mentioned above, there is a concern that corrosion may occur due to the infiltration of corrosion-causing components into the base material through this film, but when using a soft nitrided film, No corrosion occurred at the interface between the nitrocarburized film and the lubricating film, and it seems that corrosion at the interface was effectively prevented. Corrosion resistance is also improved when only the soft nitrided film is applied, but this effect is due to the fact that the resin binder in the lubricating film firmly adheres to the soft nitrided film. This seems to be because the portion covers the surface of the nitrocarburized film and is substantially protected from components that cause corrosion. As a result, the base material 1 with the soft nitrided film,
By combining the resin binder and the lubricating film 3 containing the solid lubricant 2, a thrust bearing including the base material has extremely excellent corrosion resistance even under severe conditions. Furthermore, this combination improves the load capacity compared to the case where the nitrocarburizing film is not formed, thereby providing a more suitable thrust bearing. Good sliding characteristics can be stably obtained even under harsh conditions with almost no lubricating oil. [Example] In the following example, an example of a method for forming a lubricant film containing a solid lubricant will be described. First, a base material made of a metal material (SPCC) to be treated is placed in a soft nitriding furnace, and a soft nitrided film of about 3 μm is formed on the sliding surface side of the base material. Next, a mixture of the solid lubricant and binder diluted with a suitable diluent is sprayed onto the intended sliding surface of the workpiece. and this 180
If you bake at ℃ for 30 minutes or 150℃ for 1 hour,
A desired lubricating film can be formed. The following table shows preferred examples.

[Table] Application methods include spray coating, tumbling, dipping, and brushing. In lubricating action, the lubricating film containing solid lubricant has a thickness of approximately 20 μm.
It doesn't have to be more than that. Further, the thickness including the lubricating film and the nitrocarburizing film does not need to be about 20 μm or more. A thickness of 5 to 6 μm is sufficient and the effect is almost unchanged. Due to the combined effect with the nitrocarburizing film, the lubricating film may have a thickness of about 1 μm. However, if the lubricant film is too thick, it tends to flow plastically and wear out, causing play.
It is desirable to adjust the spray conditions and the like so that the film formed during firing is less than a predetermined thickness, including the film thickness of the nitrocarburized film. It is generally desired that this value be 10 μm or less, more preferably 7 μm or less, and even better if 5 μm or less. Next, other examples of lubricating films will be shown.

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〔Effect of the invention〕

The present invention comprises a soft nitrided film applied on the sliding surface of a thrust bearing, and a lubricating film containing a resin binder and a solid lubricant formed on the soft nitrided film, so that it can be used in internal combustion engines. It is particularly effective for thrust bearings that slide under high thrust loads, such as horseshoe-shaped thrust washer bearings, as well as thrust washer bearings used in automobile differential gears, transmission gears, various machine tools, etc. do. The present invention forms a nitrocarburized coating on the sliding surface of a thrust bearing, and a lubricating coating containing a resin binder and a solid lubricant on the coating, resulting in extremely low sliding resistance and extremely large load capacity. Furthermore, excellent corrosion resistance and good sliding properties can be obtained even under harsh conditions with almost no lubricating oil. In addition, the base material can be made of easily available and inexpensive metal materials such as Fe-based alloys, and the lubricating film can be formed after soft nitriding treatment, resulting in a significant cost reduction.

[Brief explanation of drawings]

FIG. 1 is a sectional view schematically showing a cross section of a bearing according to an embodiment. DESCRIPTION OF SYMBOLS 1...Base material with nitrocarburized coating, 2...Solid lubricant, 3...Lubricating film, 4...Thrust bearing, 4a...
Thrust surface.

Claims (1)

[Scope of Claims] 1. In a thrust bearing having a sliding surface that slides under a thrust load, a soft nitrided coating is applied to the sliding surface of the thrust bearing, and a soft nitrided coating is formed on the soft nitrided coating. A thrust bearing comprising a lubricating film containing a resin binder and a solid lubricant. 2. The thrust bearing according to claim 1, wherein the solid lubricant contains at least one selected from molybdenum disulfide, graphite, boron nitride, tungsten disulfide, and polytetrafluoroethylene resin.